There’s no simple answer to this question – it depends on what you’re looking for in a lower parts kit (LPK). If you’re just looking for a basic LPK to get your AR-15 build started, then a CMMG kit will probably suffice. However, if you’re looking for top-tier performance and reliability, you’ll want to look elsewhere.
CMMG is a respectable manufacturer of AR-15 parts and accessories, but their LPKs are generally regarded as being at the budget end of the spectrum. That’s not necessarily a bad thing – budget doesn’t have to mean low quality. However, it does mean that you might not be getting the same level of quality or performance as you would from a more expensive kit.
In terms of specific parts, CMMG’s LPKs usually include a lower parts kit (LPK), buffer tube assembly (BTA), and stock. The LPK itself will contain all the small parts needed to complete your AR-15 lower receiver, including the trigger group, bolt catch, and magazine release. The BTA will include the buffer tube, buffer, and spring. And the stock will, of course, be the stock that attaches to the back of the receiver.
One potential downside of CMMG’s LPKs is that they often don’t include a trigger guard. This isn’t a huge deal, as you can usually find a trigger guard separately for relatively cheap. However, it is something to be aware of.
All in all, CMMG’s LPKs are perfectly serviceable and will get the job done. They’re not going to be the best option out there, but they’re a good budget choice.